1. Technical Field
This invention relates generally to transceivers and more particularly to an antenna arrangement for use in a portable transceiver such as a portable telephone.
2. Description of the Prior Art
A typical portable telephone includes an antenna, a transmitter and a receiver for communicating a radio frequency (r-f) carrier signal that is modulated by audio signals and switching signals to and from an associated base station as appropriate.
In most portable telephones, both the transmitter and the receiver are active at the same time and one antenna is shared for transmission and reception. This antenna is generally a telescoping whip antenna which is extended for use and retracted or collapsed when not in use. When the portable telephone is located at or near its maximum reception range from the base station, the antenna must be extended so that a user of the portable telephone can be assured of not missing an incoming call. Some users find the need to have the antenna extended for this condition inconvenient and therefore at time do not extend the antenna. With the antenna collapsed, however, the reception range of the portable telephone is approximately one-third of its range with the antenna extended.
Maximum operating range for a portable telephone is obtained when the telescoping antenna is fully extended and a resonating network, which matches to this antenna in the fully extended position, is provided. When the antenna is collapsed, however, the resonating network that matches the antenna in the extended position does not match the antenna in the collapsed position. The user of the portable telephone therefore loses somewhat more operating range than if he or she had used a non-extendible antenna that was properly matched by the resonating network.
Such a non-extendible antenna arrangement is disclosed in U.S. Pat. No. 4,721,962, issued to Heribert Gorzel on Jan. 26, 1988. This arrangement proposes totally enclosing both the transmit and receive antennas inside the housing of the portable telephone and thereby avoiding any antenna parts projecting therefrom. While this type of arrangement avoids the need to have an external antenna projecting from the portable telephone, it limits the maximum range for which the portable telephone is able to communicate with a base station simply because of the reduced antenna area available for radiating or receiving r-f energy.